Sliding contact arrangement



Feb. 19, 1963, c. P. MAJKRZAK SLIDING CONTACT ARRANGEMENT Filed Apr i1 27, 1960 INVENTOR. C. P. MAJKRZA K Wm M ATTORNEY 3,078,430 SLIDING CONTACT ARRANGEMENT Charles P. Majkrzalr, Nutley, N.J., assignor to the United States of America as represented by the Secretary of the Air Force Filed Apr. 27, 1960, Ser. No. 25,171 4 Claims. (Cl. 336-140) This invention relates to a slidable electrical contact arrangement for a helical coil, and more particularly for use in a turnable helix for electrical purposes, especially those of high power types found in turnable antennas or in antenna tuners, and has for an object the provision of a sliding contact mechanism that acts progressively to short out uniform sec-tors of the helix.

A further object is the provision of a slidable contact device for a helical tuner coil in which deviations from the true helical form, permitted by the normal manufacturing methods, do not effect the shorting out and contacting operations during the adjustments of the contact shoes or the rotation of the helix.

A further object of the invention is the provision of a multiplicity of elongated outwardly spring-pressed electrical contact shoes which are longitudinally adjustable as a unit on the inside surface of the helical tuner coil while the coil is stationary or being turned.

A further object is the provision of adjusting means for providing independent radial adjustment of the contact shoes and tilting adjustment thereof throughout radial planes extending through the central axis of the helical coil.

A further object is the provision of resilient pressure applying means at the leading edges of the elongated electrical contact shoes, constituting flexible resilient electrical contact means between the shoes and an axially adjustable support means for the shoes which is located on the central axis of the helical contact or tuner coil.

-A further object is the provision of an elongated enlarged sleeve like axially adjustable support, centrally disposed in closely spaced proximity to the inside of the helical tuner coil for slidably mounting the plurality of contact shoes in circumferentially spaced radial relation about the central axis, and yieldable radial spring means, each extending outwardly from the periphery of the sleeve means and electrically connected to the leading edge of each of the elongated contact shoes, for yielda-bly maintaining the leading edges in contact with a plurality of the helical coil turns at the opposite end portions of the shoes.

Other objects and advantages will become apparent from the following description, taken in connection with the accompanying drawings in which:

FIG. 1 is a fragmentary longitudinal sectional view, taken through a portion of a helical electrical contact coil, such as a portion of an antenna helical tuner de vice, and employing my improved electrical contact arrangement.

FIGS. 2 and 3 are somewhat schematic views illustrating the cooperating contact functions between the helical tuner coil, having certain coil turns disposed out of concentricity, and the elongated radial contact shoes, in which the shoes are illustrated in three different advanced positions in the helix, namely an upper full line position, an intermediate dotted line position and a lower dot and dash line position.

In the drawings the reference numeral 1 denotes an antenna helical tuning device or coil generally comprising a central guide tube, or hollow shaft or stem 2 on which is slidably mounted a contact supporting disc or cross head which is attached to an actuating sleeve member 4, for instance, by screw fasteners 5.

Surrounding the actuating sleeve member 4 is a cylin- 3,078,430 Patented Feb. 19, 1963 drical antenna tuning helical coil 6 comprising the turns 7 of the helical coil.

The coil 6 may consist of hollow cylindrical tubing wound in helical form having a substantially constant internal diameter and constant spacing between the coil turns 7. Due to manufacturing tolerances some of the coil turns may be out of exact concentricity, for instance, as shown in FIGS. 2 and 3 (somewhat exaggerated).

The reference numerals 9 indicate elongated electrical shoes which bridge a plurality of helical coil turns 7 in order to shunt out intermediate coil turns.

Preferably there are a plurality of these shoes 9 disposed in radial planes equally spaced circumferentially around the interior of the helical coil in contact with the inner surfaces of the coil turns. For instance, there may be four shoes 9 spaced in radial planes about the stem 2 but in the same transverse plane.

The contact shoes 9 are each formed with a cylindrical depression or recess 10 in its inner surface, midway between its upper and lower ends 9 and 9 for receivingn the outer rounded head 11 of a spring-pressed radially supported plunger or stem 12 which is slidably disposed in radial guide openings or passages 13 formed in the outer flanged portion 14 of the disc or cross head 3.

j The inner end portion of each plunger 12 is reduced concentrically in diameter to provide a stem or shank portion 15 which is slidably disposed in a radial guide passage 16 in an annular concentric upwardly extending flange surrounding the inner guide sleeve portion 17 of the cross head 3 for the tubular guide support or stem 2.

The elongated contact shoes 9 are all stabilized in parallel relation to the axis of the stern member 2 by flat flexible resilient spring-like electrical lead strips 18, connected as shown in the drawings, to the lower ends 9 of the contact shoes at one end and to the lower surface or bottom of the cross head 3 at their opposite ends.

If desired the cross head 3 may be provided with a sleeve-like extension 19 to which may be attached an annular flat metallic corona shield or disc 20.

A Washer 21 is disposed on the stem 15 of the plunger 12 and rests against the enlarged outer portion and a compression spring 22 is disposed on the stem 15 between the annular flange l6 and each washer 2-1, resiliently urging the plungers radially outward to urge the contact shoes 9 in proper predetermined contact with the inner surface of the helical coil 6.

The flat resilient contact leads or springs 18 are preferably formed as shown with a semicircular resilient por tion 18 for normally urging the lower ends 9 of the shoes outwardly and maintaining radial outward tension on the lower ends 9 of the shoes 9 as they are shifted axially along the turns 7 of the coil 6 by axial adjustment of the sleeve 4 and cross head 3.

Considerable outward pressure on the central portion of the contact shoes is maintained at all times by the plungers 12 and compression springs 22 so as to always urge the upper or trailing ends 9 of the shoes 9 into contact with the turns 7 of the coil 6 as the sleeve 4 is adjusted and while the antenna tuning coil is rotatably adjusted.

For instance, as schematically shown in FIG. 2 in full line position the lead in spring 18, by reason of the semicircular curved portion, maintains the lower or lead ing portion 9 in contact with the coil turns 7 as the shoe 9 is adjusted downwardly through the positions shown in dotted lines, and dot and dash lines.

Also during upward adjustment, as shown in FIG. 3, from the dot and dash position, through the dotted line position to the upper full line position the lower end 9* of the shoes is maintained always in contact with the lower coil turn by the resilient lead in contact member 18 while the plunger maintains outward pressure on the other end 9 to maintain the proper shunting out of the intermediate coil turn between the upper and lower ends of the contact sliders 9.

The inner end of the stern member 15 is provided with a suitable stop flange 2.3 which may be a snap washer seated in an annular groove near the inner end of the stem 15. The purpose is to limit the radial outward movement of the plungers 12, particularly when the cross head is removed from the interior of the helical coil.

It should be observed that the elongated shoes are forced into positive electrical contact as they are adjusted longitudinally by the carrier sleeve 4 and rocking of the shoes in the radial planes are permitted by the engagement of the rounded ends of the plungers 11 in the recesses or sockets to but the shoes are maintained oriented in parallel relation to the guide stem 2 by the fiat leaf spring contact members 18 which, because of the curved portion 18 maintains the lower or head portion 9 always in contact with the lower turn of the helical coil which it bridges or shunts out, regardless of a slight eccentricity of one or more of the contacted coil turns. Also the stabilizing member 18 maintains a positive electrical contact at all times and under all circumstances with the cross head.

The members 18 also retain the contact shoes 9 in properly aligned relation on the plungers 11 when the contact shoes are not confined Within the helical coil 6.

The disclosure as described specifically above and shown in the drawings in detail is for purposes of illustration rather than limitation and therefore some minor changes may be made in the construction and arrangement of parts by those skilled in the art without departing from the real spirit and purpose of the invention and it is the intention to cover by the appended claims any modified forms of structure or use of mechanical equivalents which may be reasonably included within their scope.

I claim:

1. In combination, a helical coil having substantially concentric cylindrical axially spaced coil turns, a circular cross head having its periphery disposed in adjacent spaced relation to the inner surface of said helical coil, concentric supporting means within said helical coil for supporting said cross head in concentric relation to the axis of said helical coil, a plurality of plungers radially disposed in said cross head in spaced relation circumferentially about the central axis of said circular cross head, spring means etween said cross head and said plungers for urging said plungers radially outward toward said helical coil, an elongated electrical contact shoe pivotally mounted centrally between its ends on the outer end of each of said plungers in contact with the inner surface of said helical coil, extending axially parallel to the central axis of said coil and spanning at least three of the turns of said helical coil, and pivoted for rocking movement in radial planes through the axis of said helical coil and its supporting plunger, and resilient electrical lead in contact means between one end or" said elongated contact shoe and said cross head yieldably urging said one end of said contact shoe outwardly toward the interior of said helical coil substmtia ly independently of said spring means for said plungers.

2. in combination, a helical tuner coil rotatable about its axis, comprising substantially concentric helical coil turns disposed in axially spaced relation, a circular cross head having its periphery disposed in adjacent spaced relation to the inner surface of said helical coil, a central guide member fixed in the helical coil for guiding said cross head longitudinally on the axis of said helical coil, annular sleeve means within said helical coil connected to said cross head for adjusting said cross head longitudinally within said helical coil, a plurality of helical coil contact plungers radially disposed in said cross head in spaced circumferential relation around the central axis of said helical coil normal to said central axis, spring means between each of said plungers and said cross head for independently urging said plungers radially outward toward said helical coil, an elongated electrical contact shoe pivotally mounted centrally between its opposite ends on the outer end of each plunger, said elongated contact shoes having their length dimensions disposed parallel to the central axis of said helical coil and having a length between its opposite ends suificient to span at least three coil turns of said helical coil, and a flat contact leaf spring fixed to the bottom of said cross head and extending radially outward into contact with the lower end of said contact shoe for urging said lower end outward toward said helical coil independently of the aforesaid spring means.

3. Apparatus as set forth in claim 2, in which the pivotal connection between the outer end of said plunger and said contact shoe is provided by a central recess formed in the back surface of each of the elongated contact shoes having a bottom surface receiving the outer end of said plunger, and the outer end of the plunger is formed with a rounded head seated in the recess against the said bottom thereof.

4. Apparatus as claimed in claim 3, in which said flat leaf spring means is formed with a U-shaped rebent portion intermediate said cross head and the back of said contact shoe to provide a resilient intermediate portion, and the outer end of said leaf spring is secured to the lower end of said contact shoe, and the opposite end of said leaf spring means is fixed to said cross head, for resiliently maintaining said contact shoe in said parallel relation to the axis of said helical coil in a radial plane through said axis and maintain positive electrical contact between said cross head and said contact shoe.

References Cited in the file of this patent UNITED STATES PATENTS 2,324,189 Bock July 13, 1943 2,425,411 Zottu Aug. 12, 1947 2,757,348 Gray July 31, 1956 2,910,661 Glynn Oct. 27, 1959 

1. IN COMBINATION, A HELICAL COIL HAVING SUBSTANTIALLY CONCENTRIC CYLINDRICAL AXIALLY SPACED COIL TURNS, A CIRCULAR CROSS HEAD HAVING ITS PERIPHERY DISPOSED IN ADJACENT SPACED RELATION TO THE INNER SURFACE OF SAID HELICAL COIL, CONCENTRIC SUPPORTING MEANS WITHIN SAID HELICAL COIL, CONCENTRIC SUPPORTING MEANS WITHIN SAID HELICAL COIL FOR SUPPORTING SAID CROSS HEAD IN CONCENTRIC RELATION TO THE AXIS OF SAID HELICAL COIL, A PLURALITY OF PLUNGERS RADIALLY DISPOSED IN SAID CROSS HEAD IN SPACED RELATION CIRCUMFERENTIALLY ABOUT THE CENTRAL AXIS OF SAID CIRCULAR CROSS HEAD, SPRING MEANS BETWEEN SAID CROSS HEAD AND SAID PLUNGERS FOR URGING SAID PLUNGERS RADIALLY OUTWARD TOWARD SAID HELICAL COIL, AN ELONGATED ELECTRICAL CONTACT SHOE PIVOTALLY MOUNTED CENTRALLY BETWEEN ITS ENDS ON THE OUTER END OF EACH OF SAID PLUNGERS IN CONTACT WITH THE INNER SURFACE OF SAID HELICAL COIL, EXTENDING AXIALLY PARALLEL TO THE CENTRAL AXIS OF SAID COIL AND SPANNING AT LEAST THREE OF THE TURNS OF SAID HELICAL COIL, AND PIVOTED FOR ROCKING MOVEMENT IN RADIAL PLANES THROUGH THE AXIS OF SAID HELICAL COIL AND ITS SUPPORTING PLUNGER, AND RESILIENT ELECTRICAL "LEAD IN" CONTACT MEANS BETWEEN ONE END OF SAID ELONGATED CONTACT SHOE AND SAID CROSS HEAD YIELDABLY URGING SAID ONE END OF SAID CONTACT SHOE OUTWARDLY TOWARD THE INTERIOR OF SAID HELICAL COIL SUBSTANTIALLY INDEPENDENTLY OF SAID SPRING MEANS FOR SAID PLUNGERS. 